Electric hammer



K. OLSEN ELECTRIC HAMMER Filed Aug. 16. 192s Dec. 18, 1928. 1,695,780

gmmtw K o n re :1 Olsen Patented Dec. 18, 1 928. I p

KONRAD OLSEN, F TACOMA, WASHINGTON.-

ELECTRIC HAMMER.

Application filed August 16, 1926. Serial No. 129,545 I This invention relates to electrically driven percussion tools, such as hammers and chisels, and has for its objects to improve thejconstruction of such a tool whereby, first, the

'5 spring delivering the blow will be of considerablelength and maytherefore be comparatively heavy, thereby delivering a'strong blow without overstrain; second, the electric motor may run at a very high speed, and therefore may be of comparativelysmall dimensions and weight; third, the gears interposed between the'm'otor and the actuating cam are of the spur gear type and are mounted within an oil bath and therefore are ex-- tremely rugged in construction and'of long life; fourth, the hammer portion ofthe tool may be removed from the motor portion thereof and, since the drive shaft is of comparatively slow speed, a drilling tool may be mounted thereon, thereby permitting the same'electric equipment to be applied to a plurality of. types of tools; and fifth, the

speed of the blows is high in spite -:of the low speed of said drive shaft.- A further object which will-be of low cost to manufacture and to operate and which will be highly efficient in use. i

I attain these and. other objects by. the

mechanisms, devices and arrangements illustrated in the accompanying drawings,

Fig.1 is a side elevation, partly in section,

to reveal the interior of the gear box, of the electric motor portion of my improved tool,

the hammer portion thereof having been removed; Fig. 2 is a horizontal section of my improvedhainmer, showing'the electric motor portion therein in plan Fig. 3 is a side -view of: the complete tool, showing the hammer portion and'a portion of the gear box in section; Fig. 4 is an end elevation of the motor portion after-the hammer portion of the tool has been removed and showingthe opera ating cam; and Fig. 5 is a section of the frame of the hammer portion, taken at the level of the line marked A; in Fig] 3,- with the plunger removed and showing the bushing therein. Y

similar parts throughout the several views.

Referring to the drawings, the electric motor 1 is preferably of the cylindrical type and is provided with a rapidly rotating armature shaft 2, projecting axially therefrom. The frame of the motor is provided with suitis to provide such an electrically driven tool Similar numerals of: reference refer to able securing flanges 3. The other details of the electric motor arenot illustrated herein as they form no part of my invention.

A gearbox 4, preferably of about the same diameter as the electric motor 1, is provided with securing flanges 5, complementary to the flanges 3 on the motor, and the two parts; are secured together by bolts 6, or otherwise." The gear box 4 comprises a hollow casting forming a space 7 within which the gears-are mounted and forming an oil compartment adapted to be filled with oil or grease. -A wall 8 is secured withinthe box 4to form a closure for the said oil compartment 7. .A'

drive shaft 9 is mounted in a broad bearing formed in the wall 8, coaxial with the armature shaft 2 of themotor. A counter shaft 10 is mounted parallelwith the shafts 2 and 9. A pinion 11 is mounted on the armature shaft 2 and meshes with a larger gear 12 on'the counter shaft 10, and this shaftalso carries a pinion 13, which meshes with the larger gear 14 mounted onthe drive shaft 9. Thus the drive shaft 9' turns in the same direction as the armature shaft 2 but at amuch lower speed. 3 1 e The cylindrical walls 'of the gear box 4 extend out beyond-the above mentioned closure wall 8 and thus form a cam chamberl5 inthe end of the gearbox. The said drive shaft 9 projects into the said cam chamber 15 and may be screw-threadedat its end, or.

provided with other securing means if desired. The box 4 is also provided with securing flanges 16 at the'cam chamber endthereof; As shown in Fig. 1, when the hammer portion of the t'o'ol'is removed, the cam'cham-.,

ber 15 is open and the end of the drive shaft 9 is exposed and is adapted to receive a drill chuck, or'other tool-securing means. v

A cam'disk 17 is mounted in the chamber 15 and 'isprovided witha central. boss 18 adapted to screw on the end of the drive shaft 9. The disk 17 is cut away on its outer face, as shown in Figs. 3 and 4, to form three or more curved eccentric cam surfaces 19, each leading inward from an outer concentric cir-= cular are 20 and terminating in a radial surface 21 leading outward from the inner end of the eccentricsurface 19 to theme 20.

The hammer part of the tool' comprises a 1 frame having a circularfdisk or plate'22 withflanges 23, complementary to the flanges 16 of the gear box 4, said plate being adapted to close the cam chamber 15 when secured thereon by bolts 24, passing through the said plug 29,

flangeslo and 23. The plate 22 is preferably formed integral with the tubular hammer casing 25 which extends with its axis at rightangles to the axis of the motor 1 and gear box l. The casing 25 is provided with a removable handle 26, of conventional form, and containing an electric switch operated by the lever 27, in the usual way. The power wires lead to the handle 26 through a push plu 23, as usual, and the wires leading from the handle 26 to the motor 1 may also be connected tothe handle 26 by a suitable push if desired, whereby, when the motor 1 is used independent of the hammer, it may be quickly diseng ed from the handle A slot 30 is formed through the side wall oi the casing 25 and the plate 22, connecting the lower part of the cam chamber 15 with the inside of the said tubular casing and adapted to permit the operating pin to freely reciprocate therein. A bushing is mounted in the lower end of the tubular ing 25, the upper end" 31 of which provided with a square axial hole and/the lower end 32 with a circular axial hole, the diameter of the latter being equal to the diagonal oi' the former (Fig. 5):. A hammer plunger is mounted in the tubular casing, said plunger comprising a square sectioned striking head 33, mounted in the square hole in: the bushing and projecting down therefrom into the round holetherein, and adapted to forcefully strike whatever tool end may be mounted in the said round portion oi the bushing; a cylindrical operating head 34, above the striking head- 33 and above the bushing 31; and along upper shank 35, extending through a screw plug 36 in the upperend of the tubular :as- 25. A strong helical spring 37 is mounted within the casing 25, surrounding the f-llltLYil-Z and is compressed between the plug and the upper surface of the operating head 34, and is adapted to strongly drive the oywrating head 34. ant. striking head 33 when thehead 3% is released. An operating pin oasses horizontally through the operatinghead 34 and projects through the slot 30 and into the cam chamber 15, and is provided with a roller, 39 at its end, adapted to engage theececntric cam Stll'fiLCG 19 and to be raised thereby to compress the spring 37, as the-cam rotates, and to be released when the radial surface 21 is reached, whereby the hammer plunger is released. The length of the slot 30- is such that'when: the plunger is at either end of its stroke the pin 38 is free from engagement from the end of the slot, and the position otthe bushi. r 31 is such that the operating head 34 will be in engagement therewith before the roller 39 comes in contact with the circular arc.20 of the cam, thus the pin and the cam disk are both relieved ot all the shock of the hammer blows, and

the full force thereof is received by the tool in the bushing Also the square bushing 31 carries allthe rque due to the action of the cam 19 on the pin 38 and therefore there is no wear of the said pin on the sides of'the slot 30. It will also be observed that the shank 35 is mounted between bearings in the parts 31 and 36 and that the operating force is applied thereto between the said bearings, and that therefore the operating force may be applied thereto in a line outside of the axis of the hammer without having'to make the said parts heavy to overcome thebending moment applied thereto. it w ll also be ob without lengthening the whole tool than would be possible with the motor coaxial; with the hammer. Also that though the motor or high speed, the drive shaft is of low speed and is therefore adapted tor other uses than with tl particular hammer, and that tnough the. drive shaft is of low speed the recipro :ations of the hammer are of high; speed. Also that the circular arc of the cam between each radial part and the adjacent combination of served that with this arrangement of parts it is possible to use a much longer. spring bushing adjacent said tool bushing; a second bearing bushing at the handle end of the tube; a hammer rod extending within said tube through both said bearing bushings, and adapted to reciprocate therein; a weight se cured to said rod, between the bearing bushings and near the lower end thereof; a long. helical spring mounted within. said tube and surrounding. said hammer rod and compressed between said upper bearing bushing, and said weight, whereby said rod, with the weight, is actuated downward to engagethe tool; a cam arranged adjacent said weightand rotating on an axis; at right angles to the 's of said rod pond apin. secured to said weight and engaging said cam,v whereby the" KO-NRAD o snn; 

